Solvent for dewaxing



Dec. 1, 1942. J. v. MONTGOMERY ETAL 2,303,570

SOLVENT FOR DEWAXING Filed Sept. 30, 1940 LOWERING OF MISCIBILJTY TEMPERATURE, 'F A 2 4 6 8 IO H 12' PERCENT MATERIAL ADDED TO PICOLINE SOLVENT PERCENT BY VOLUME INVENTORJ J.V. MONTGOMERY L. B. GOODSON I ATTOR Y Patented Dec. 1, 1942 SOLVENT FOR, DEWAXING James V. Montgomery, Okmulgee, Okla., Luke B. Goodson, Phillips, Tex., and Robert W. Henry, Bartlesville, kla., assignors to Phillips Petroleum Company, a corporation of Delaware Application September 30, 1940, Serial No. 359,164

2 Claims.

This invention relates to mineral oil refining, and more particularly'it relates to an improved dewaxing solvent.

It is known to use heterocyclic nitrogen base compounds such as pyridine, picolines, lutidines, collidines, etc., as extraction and dewaxing solvents, and it is known to use these nitrogen base :solvents in conjunction with certain wax anti- :solvents or solubility enhancing agents. In an application filed by James V. Montgomery and Robert W. Hem'y, Serial No. 358,342, filed September 25, 1940, it was proposed to add to such solvents as picolines, and those mentioned above, certain organic compounds having the property of lowering the miscibility temperature with waxy oil, and assisting with the removal of water from the solvent system. These organic addition agents in order to exhibit maximrun utility must possess boiling points below approximately 200 F., for example, it was suggested to add benzene, boiling point about 177 F., to the wet picoline solvent. Picolines and water form a physical mixture boiling at a constant temperature of approximately 200 F.

An object of this invention is to furnish an improved solvent for the dewaxing of lubricating oil stocks.

Another object of this invention is to furnish a, dewaxing solvent which has an increased tolerance for dissolved water.

Still other objects and advantages will be apparent from a study of the disclosure that follows. We now propose to improve the utility of pioolines and similar solvents by adding thereto certain organic compounds which lower the miscibility temperature of the solvent with waxy oils, increase the dewaxing selectivity of the solvent, and which have higher boiling points than those specified in the above-mentioned application. These organic compounds are termed solubility enhancing agents. Our added solubility enhancing agents are in themselves selective and their presence in the solvent mixture not only lowers the miscibility temperature of the solvent and the oil to be dewaxed, but also increases the wax selectivity thereof. Since these compounds have higher boiling points they do not so readily assist in the removal of undesirable water from the solvent system, but they do increase the tolerance of picolines and the like for water and thus improve the utilityof the solvent.

Compounds suitable for use according to our invention include such as:

Terpenes of the type of limonene, menthane,

menthene, pinene,

Alkyl sulfides such as butyl, amyl sulfides,

Amines such as hexyl, heptyl amines,

Mercaptans such as butyl, amyl, phenyl mercaptans,

Sulfur oils from gasoline caustic wash,

Thiophene, and alkyl derivatives.

The figure shows the relation of the miscibility temperature lowering and the amount of added material in the solvent.

Referring to the figure, it is seen that a relatively small amount of limonene (percent by volume) added to a picoline solvent materially lowers the miscibility temperature of the oil-solvent mixture, for example 5% limonene in the picoline solvent lowers the miscibility temperature 10 F.

In another example, not shown in the accompanying graph, 5% limonene in a picoline solvent lowered the miscibility temperature of a waxy long residuum stock 9 F., from minus 14 F. to minus 23 F.

Of the compounds tested, limonene, diamyl sulfide and amyl mercaptan were found to be the most effective for lowering the miscibility temperature of the picoline-011 mixture.

In carrying out our invention, we do not wish to be limited by any special type of dewaxing apparatus, since essentially any standard dewaxing equipment should be satisfactory. For dewaxing of the above mentioned long residuum stock at minus 20 F., the oil to be dewaxed is mixed with a picoline solvent containing 5% by volume (of the picoline solvent) of limonene,

combined filtrate solution and washings comprising dewaxed oil and solvent mixture are conducted to a solvent-oil separating apparatus. This separating apparatus may comprise a conventional pipe heater and fractionating tower from which the solvent mixture is removed overhead as vapors and the oil exits from the lower portion thereof and is conducted to storage.

The solvent vapors from the above mentioned fractionator are condenser and the solvent mixture conducted to intermediate storage preparatory to reuse.

The used solvent mixture may contain a minute amount of moisture which had been extracted by the picoline solvent from the oil being dewaxed. Water tends to raise the miscibility temperature of a picoline and oil mixture, but to offset this increase in miscibility temperature, a quantity of limonene had previously been added. Hence, the addition of this limonene had increased the toleration of the picoline solvent for water.

By occasional further additions of such materials as above mentioned, an example being limonene, picoline solvents or similar solvents may be used for extended periods of time without the necessity of having to be dehydrated or dried. Thus, the utility of picoline solvents is materially extended.

While we have described the use of limonene in a picoline dewaxing solvent, we do not wish to be limited in this manner since the materials or compounds heretofore mentioned function favorably in extending the utility of such solvents as the isomeric picolines, pyridine, lutidines, collidines,. etc., or mixtures of the same such as occur in commercial pyridine.

We claim:

1. The process of dewaxing mineral oils including the steps of mixing the waxy oil with a dewaxing solvent comprising a heterocycllc nitrogen base solvent, and limonene as a solubility enhancing agent, chilling the oil-solvent mixture to precipitate the wax, and removin the precipitated wax.

2. The process of dewaxing mineral oils including the steps of mixing the waxy oil with a dewaxing solvent comprising picoline, and limonene as a solubility enhancing agent, chilling the oil-solvent mixture to precipitate the wax, and removing the precipitated wax.

JAMES V. MONTGOMERY. LUKE B. GOODSON. ROBERT W. HENRY. 

